I'm singleton.

Implementing the singleton design pattern in C++

This is a foundational C++ coding problem that tests your understanding of how to enforce the singleton design pattern—a constraint that prevents instantiation of more than one object of a given class. Quant firms and other performance-critical systems rely on singletons for global state like loggers, configuration managers, and resource pools, so knowing how to implement them correctly matters.

The core challenge is to block the compiler's default copy and move constructors while providing a controlled static method to access a single, lazily-initialized (or eagerly-initialized) instance. A solution must be both thread-safe in the declaration and explicit in preventing unintended duplication. Interviewers often follow up by asking about thread safety, initialization order, and whether you'd use a pointer or reference to return the instance.

• Deleted copy and move constructors
• Static instance storage and access
• Private constructors and factory methods
• Thread-safe initialization strategies